Unsaturated lactones and lactams occur widely in nature. Their extensive phyiological activity has already found application in the clinic and promises considerable medicinal utility in the treatment of cancer, circulatory and heart ailments, and fungal and bacterial infections. A wide range of other antibiotic activity is anticipated. Our recent work on the carbonylation of vinylmercurials has provided a novel new route from propargylic alcohols to a variety of delta varies as, beta-butenolides, including tetronic acids. Palladium promoted carbonylation of acetylenic phenols should provide coumarins and coumestans. The mercuration-carbonylation of propargylic amines offers a novel route to delta 3-pyrrolin-2-ones such as the antitumor agent tenuazonic acid. Thallation and palladium catalyzed carbonylation of benzylic and beta-phenethyl alcohol derivatives leads to phthalides and 3,4-dihydroisocoumarins, as well as coumarins. All of these palladium promoted carbonylation reactions start with readily available starting materials, proceed in good yield under exceedingly mild reaction conditions, and appear to tolerate considerable organic functionality. These valuable new synthetic procedures offer real advantages over present synthetic routes to these physiologically active ring systems and should provide a number of new unsaturated lactones and lactams possessing interesting biological activity and holding promise of medicinal utility.